Unlike conventional small‐molecule drugs, many of which can be formulated effectively with excipients to avoid degradation in the stomach and which exhibit reasonably efficient uptake through the gastrointestinal tract, biological drugs may exhibit lower stability and a greater sensitivity to enzymatic degradation, making oral delivery problematic. Thus, the majority of biologics are currently administered through subcutaneous/intramuscular injection or via intravenous infusion. Recent advances in delivery of traditional biologics include methods to increase the acceptable volume of drug solutions that can be administered subcutaneously.In addition, a number of alternative routes of administration for biologic drug products are being intensively investigated at the preclinical and clinical stages, such as intranasal, pulmonary, transcutaneous, and other routes, with some first examples of products recently licensed.This chapter will review current methods in use for marketed biologics and advanced approaches undergoing clinical testing.